JP2007160586A - Resin molded product and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of a crack in the boundary of an expanded panel with a solid panel part in a resin molded product molded by expansion molding. <P>SOLUTION: At the time of expansion molding, a cavity volume is magnified in a state in which a thermoplastic resin is much charged in the cavity place corresponding to the boundary of the expansion panel part 3 with the solid panel part 9 in a direction more magnifying the cavity volume than its periphery to mold a panel-shaped carrier plate 1 by the expansion panel part 3 and the solid panel part 9. The panel thickness T1 of the expansion panel part 3 is formed so as to be made larger than the panel thickness T2 of the solid panel part 9 and an erected wall 21 comprising a solid layer 20 erected in the panel thickness direction is formed to the boundary of the expansion panel part 3 and the solid panel part 9. The protruded part 23 comprising the solid layer is integrally formed to the leading end in the panel thickness direction of the erected wall 21 so as to be more largely protruded than the panel surface 3a of the expansion panel part 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a panel-like resin composed of an expansion panel portion having a skin layer formed on the surface and an expansion layer having a large number of voids formed therein, and a solid panel portion adjacent to the expansion panel portion. The present invention relates to a molded body and a molding method thereof.

In Patent Literature 1, a thermoplastic resin containing fibers is injected and filled into a cavity in a state in which a mold composed of a movable mold and a stationary mold containing a movable mold is closed, and the thermoplastic resin is filled in the cavity. In the process of solidifying, the movable mold is retracted in the moving mold in the direction of increasing the cavity volume, and the thermoplastic resin is expanded by the elastic restoring force (spring back phenomenon) of the fiber compressed by the mold. In addition, a resin molded body is obtained in which a skin layer is formed on the surface and an expansion layer having a large number of voids is formed inside. And in this resin molding, weight reduction is achieved by forming the said expansion layer in the whole panel panel of a resin molding. Further, in Patent Document 1, a gap is formed between the side surface of the movable mold and the side surface of the movable mold, and the gap is filled with a thermoplastic resin, so that the molding surface of the resin molded body is moved to the molding surface when the movable mold is retracted. The appearance of the side appearance of the resin molded body is improved by eliminating adverse effects.
Japanese Patent Laid-Open No. 11-156881 (paragraph 0033 column, FIG. 2)

  By the way, when attaching a part to the resin molding in which the expansion layer is formed over the entire panel as described above, it is conceivable to increase the rigidity by forming the part attachment portion with a solid layer without the expansion layer.

  However, in the resin molded body in which the solid panel portion made of the solid layer is adjacent to the expansion panel portion having the expansion layer in this way, when the expansion volume of the mold is expanded to form the expansion layer of the expansion panel portion, the expansion panel Since the resin being solidified (solidified) is pulled in the thickness direction on the movable molding surface at the boundary of the solid panel part of the part, a crack occurs in the part and the strength rigidity of the resin molded body decreases. Become.

  The present invention has been made in view of such points, and the object of the present invention is to prevent cracks from occurring at the boundary between the expanded panel portion and the solid panel portion in the expanded resin molded body. is there.

  In order to achieve the above object, the present invention is characterized in that the structure of the boundary portion between the expansion panel portion and the solid panel portion is devised, and the following solution is taken.

  That is, according to the first aspect of the present invention, in the process of solidifying the injection-filled thermoplastic resin in the mold cavity, the cavity layer is expanded to expand the thermoplastic resin, so that the skin layer is on the surface. An expansion panel portion formed inside with an expansion layer having a large number of voids, and a solid panel portion formed of a solid layer adjacent to the expansion panel portion and formed without expanding the cavity volume during molding A panel-shaped resin molded body configured, and at the time of expansion molding, a thermoplastic resin is placed in a cavity portion corresponding to a boundary between the expansion panel portion and the solid panel portion in a direction in which the cavity volume is larger than the surroundings. By expanding the cavity volume in a filled state, the expansion panel portion is formed thicker than the solid panel portion. In both cases, a standing wall made of a solid layer standing in the thickness direction is formed at the boundary of the expansion panel portion with the solid panel portion, and higher than the panel surface of the expansion panel portion at the front end in the thickness direction of the standing wall. A protruding portion made of a solid layer is integrally formed so as to protrude.

  The invention according to claim 2 is a method of molding a resin molded body according to claim 1, wherein the fixed mold, a movable mold that is opposed to the fixed mold so as to be able to advance and retreat, and the movable mold side A chamfered portion formed on the molding surface of the movable mold so that there is a gap between the slide mold and the side surface of the slide mold. In the state where the mold is closed so that the molding surfaces of the movable mold and the slide mold are substantially flush with each other, a thermoplastic resin is injected and filled into the cavity of the mold. In the process of solidifying the thermoplastic resin, the slide mold is not retracted, and only the movable mold is retracted in the mold opening direction to expand the thermoplastic resin corresponding to the movable mold.

The invention according to claim 3 is the invention according to claim 2,
The relationship between the height (H) of the chamfered portion in the mold opening direction and the expansion ratio (W) of the thermoplastic resin is expressed by the following equation:
H ≧ W × 1 / 2mm
While satisfying
The width (D) of the chamfered portion along the molding surface of the movable mold is the following formula:
5 ≧ D ≧ 1mm
The filling,
The space length (L) in the mold opening direction of the cavity space corresponding to the expansion panel portion when the mold is closed is expressed by the following formula:
6 ≧ L ≧ 1.5mm
It is characterized by satisfying.

  According to the first aspect of the present invention, the skin layer is formed on the surface of the expansion panel portion, and the expansion layer having a large number of voids is formed therein, so that the weight of the resin molded body can be reduced. Moreover, since the solid panel part adjacent to the said expansion | swelling panel part is formed with the solid layer, the strength rigidity of this solid panel part can be improved. In addition, an upright wall made of a solid layer is formed at the boundary between the expansion panel portion and the solid panel portion, and the raised portion made of the solid layer protrudes higher than the panel surface of the expansion panel portion at the end of the upright wall. In the expansion molding, the thermoplastic resin of the standing wall portion is filled in advance in the direction in which the cavity volume expands more than the surrounding area, and the molding surface of the molding die is in the plate thickness direction. Therefore, the standing wall is not cracked, and the strength and rigidity of the resin molded body can be ensured. In addition, since the raised portion is integrally formed with the standing wall and functions as a rib, the strength rigidity in the vicinity of the boundary is further improved.

  According to the second aspect of the present invention, the mold structure can be greatly improved by simply forming a chamfered portion in the movable mold forming surface adjacent to the slide mold so as to have a gap between the side surface of the slide mold. The resin molded body according to claim 1 can be easily molded without modification.

  According to the invention of claim 3, by appropriately setting the dimension of the chamfered portion formed on the molding surface of the movable mold in relation to the expansion ratio of the thermoplastic resin and the dimension of the cavity space in the mold opening direction. Thus, it is possible to reliably obtain a resin molded body that is lightweight and has improved strength and rigidity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a perspective view of a panel-shaped resin carrier plate (door module) 1 constituting a part of a side door of an automobile as a resin molded body according to an embodiment of the present invention as viewed from the vehicle interior side. Although not shown, the carrier plate 1 is assembled to the door inner panel of the door main body including a door outer panel and a door inner panel, and the door trim covers the carrier plate 1 from the vehicle interior side. Attached to.

  The carrier plate 1 includes an expansion panel portion 3 that forms the main body (plate body), and a plurality of cylindrical attachments for attaching the carrier plate 1 to the door inner panel on the outer peripheral edge of the expansion panel portion 3. The seat 5 is integrally formed over the entire circumference with a predetermined interval, and an annular speaker mounting portion 7 is integrally formed in the lower left of FIG. Further, on the diagonally upper right side of the speaker mounting portion 7 in FIG. 2, a substantially triangular solid panel portion 9 that constitutes the carrier plate 1 with the expansion panel portion 3 is integrally adjacent to the expansion panel portion 3. A circular motor mounting hole 11 for mounting a wind glass lifting / lowering motor (not shown) is formed at the substantially center of the solid panel portion 9, and there are three around the motor mounting hole 11. The through hole 13 for screw insertion is formed corresponding to the position of the apex of the triangle.

  As shown in FIG. 1, the expansion panel portion 3 has a cavity volume corresponding to the expansion panel portion 3 in the process of solidifying the fiber-filled thermoplastic resin R injected and filled in a cavity 33 of a mold 25 to be described later. By enlarging and expanding the thermoplastic resin R by the elastic restoring force (expansion force) of the fibers (not shown), a rigid skin layer 15 without voids is formed on the surface, and a large number of voids (not shown). Is formed inside so as to bulge out toward the passenger compartment. On the other hand, the solid panel portion 9 includes a solid solid layer 19 that does not expand the cavity volume corresponding to the solid panel portion 9 and does not have the expansion layer 17 at the time of molding. Therefore, the plate thickness T1 of the expansion panel portion 3 is thicker than the plate thickness T2 of the solid panel portion 9. In addition, a standing wall 21 made of a solid solid layer 19 standing in the plate thickness direction is formed at the boundary between the expansion panel portion 3 and the solid panel portion 9. Furthermore, as a feature of the present invention, a protruding portion having a substantially triangular cross section made of a solid layer is projected at the front end in the thickness direction of the upright wall 21 so as to protrude higher than the panel surface 3a on the vehicle interior side of the expansion panel portion 3. 23 is integrally formed. The rising wall 21 and the raised portion 23 are formed in such a direction that the thermoplastic resin R is applied to the cavity portion corresponding to the boundary between the expanded panel portion 3 and the solid panel portion 9 in the direction in which the cavity volume is larger than the surrounding area during expansion molding. Molding is performed by enlarging the volume of the cavity in a filled state.

  As described above, the skin layer 15 is formed on the entire surface of the expansion panel portion 3 and the expansion layer 17 having a large number of voids therein is formed, whereby the weight of the carrier plate 1 can be reduced. Further, since the solid panel portion 9 is formed of the solid solid layer 19 having no expansion layer 17, the strength and rigidity of the solid panel portion 9 is increased, and the wind glass raising / lowering motor is stably attached to the solid panel portion 9. Can be attached. Further, since the raised portion 23 is integrally formed with the standing wall 21 and functions as a rib, the strength rigidity in the vicinity of the boundary is further improved.

  Such a carrier plate 1 is molded by a molding die 25 as shown in FIGS.

  The mold 25 includes a fixed mold 27, a movable mold 29 that is opposed to the fixed mold 27 so as to be movable back and forth, and a slide mold 31 for molding the solid panel portion 9 provided on the movable mold 29 side. It has. The slide mold 31 is inserted into an insertion hole 29a formed corresponding to the solid panel portion 9 of the movable mold 29 so as to be relatively movable, and a spring, a cylinder, etc. so as to protrude toward the fixed mold 27 side. It is energized by the energizing means (not shown). Further, a large-diameter convex portion 31 b is integrally projected on the molding surface 31 a of the slide mold 31 so as to correspond to the motor mounting hole 11, and three small-diameter convex portions 31 c correspond to the through-hole 13. And projecting together. Then, with the mold 25 closed, the tip surfaces of the protrusions 31b and 31c of the slide mold 31 are brought into contact with the molding surface 27a of the fixed mold 27, and the molding surface 27a of the fixed mold 27 and the movable mold 29 and the molding surfaces 29b and 31a of the slide mold 31 are formed with cavities 33. Further, a chamfered portion formed by an inclined surface that is notched obliquely so as to have a gap C between the side surface 31d of the slide mold 31 and a portion of the molding surface 29b of the movable mold 29 adjacent to the slide mold 31. 29c is formed.

In particular, in the mold 25, the relationship between the height (H) of the chamfered portion 29c in the mold opening direction and the expansion ratio (W) of the thermoplastic resin R is expressed by the following equation.
H ≧ W × 1 / 2mm
It is set to satisfy.

  Here, the expansion ratio (W) of the thermoplastic resin R may be 2.0 times or more. Accordingly, the height (H) of the chamfered portion 29c in the mold opening direction is at least 1 mm. If the length is less than 1 mm, the amount of the thermoplastic resin R filled in the gap C at the time of expansion molding is insufficient with respect to the expansion ratio (W) = 2.0. This is because the movable die 29 is pulled in the plate thickness direction as the movable die 29 retreats in the mold opening direction, and the standing wall 21 is cracked. The upper limit of the height (H) in the mold opening direction of the chamfered portion 29c is not preferable because the protruding amount of the raised portion 23 becomes unnecessarily large when the numerical value becomes too large, and is appropriately determined according to the purpose of use. The

Further, the width (D) of the chamfered portion 29c along the molding surface 29b of the movable mold 29 is expressed by the following formula.
5 ≧ D ≧ 1mm
It is set to satisfy.

  The reason for this setting is that if the width (D) of the chamfered portion 29c is less than 1 mm, the solid layer 20 of the standing wall 21 becomes too thin and cracks are likely to occur during expansion molding. On the other hand, if the thickness exceeds 5 mm, the thickness of the solid layer 20 and the raised portion 23 of the standing wall 21 in the width direction becomes too thick, and the weight reduction cannot be promoted.

Further, the space length (L) in the mold opening direction (plate thickness direction) of the cavity space corresponding to the expansion panel portion 3 at the time of mold closing is expressed by the following formula.
6 ≧ L ≧ 1.5mm
It is set to satisfy.

  The reason for this is that if the space length (L) is less than 1.5 mm, the rigidity of the expansion panel portion 3 is reduced, whereas if it exceeds 6 mm, the entire carrier plate 1 becomes too thick to promote weight reduction. It is not possible. The space length in the mold opening direction of the cavity space corresponding to the solid panel portion 9 is set to be equal to the space length (L).

  Thus, by appropriately setting the dimension of the chamfered portion 29c of the movable mold 29 in relation to the expansion ratio (W) of the thermoplastic resin R and the space length (L) in the mold opening direction of the cavity space, The carrier plate 1 that is lightweight and improved in rigidity can be reliably obtained.

  Incidentally, the expansion ratio (W) of the thermoplastic resin R is 2.0 times, the space length (L) in the mold opening direction of the cavity space is 1.5 mm, the width (D) of the chamfered portion 29c is 0 mm, and the chamfered portion 29c. When the height (H) in the mold opening direction is 0 mm, cracks occurred in the standing wall 21 of the expansion panel portion 3, but the expansion ratio (W) of the thermoplastic resin R was 2.0 times, and the mold in the cavity space When the space length (L) in the opening direction was 1.5 mm, the width (D) of the chamfered portion 29c was 1 mm, and the height (H) in the mold opening direction of the chamfered portion 29c was 1 mm, no crack occurred.

  Next, the point which shape | molds the carrier plate 1 using the said shaping | molding die 25 is demonstrated.

  First, as shown in FIG. 3, an injection machine (not shown) is placed in the cavity 33 with the mold 25 closed so that the molding surfaces 29b and 31a of the movable mold 29 and the slide mold 31 are substantially flush with each other. ) From a glass-filled thermoplastic resin R (for example, a fiber-filled polypropylene resin). In this state, the thermoplastic resin R is filled in a gap C formed between the chamfered portion 29c of the movable die 29 and the side surface 31d of the slide die 31.

  Thereafter, the skin layer 15 is generated in the process of solidifying the thermoplastic resin R in the cavity 33 of the mold 25, that is, in the vicinity of the molding surfaces 27 a and 29 b of the mold 25 (fixed mold 27 and movable mold 29) in the cavity 33. At this point, as shown in FIG. 4, the slide mold 31 is not retracted, but only the movable mold 29 is retracted in the mold opening direction A in which the cavity volume is increased. That is, the movable mold 29 is slightly separated from the fixed mold 27, and the cavity volume corresponding to the expansion panel portion 3 is expanded to, for example, twice (expansion magnification (W) = 2.0) or more. At this stage, the thermoplastic resin R is hard without voids because the portions of the mold 25 (the fixed mold 27 and the movable mold 29) that contact the molding surfaces 27a and 29b are cooled early due to the influence of the mold temperature. It becomes the skin layer 15 and constitutes the surface layer. On the other hand, the inner part of the thermoplastic resin R is hardly affected by the mold temperature and is in a gel state with high viscosity. Therefore, by increasing the cavity volume, the fibers that have been compressed by the fixed mold 27 and the movable mold 29 until then are released from the compression and elastically restored, and the elastic restoring force (springback phenomenon), that is, the expansion pressure described above. The thermoplastic resin R expands. As a result, a hard skin layer 15 having no voids is formed on the surface, and the expansion panel portion 3 in which the expansion layer 17 having a large number of voids (not shown) is formed inside the expansion panel portion 3 is the carrier plate. 1 is formed. Thereby, compared with the case where the expansion panel part 3 consists only of the solid layer 19 which does not have the expansion layer 17, and is the same thickness as the expansion panel part 3 of this embodiment, weight reduction of the carrier plate 1 can be achieved. it can. Further, an upright wall 21 made of a hard solid layer 20 is formed at the boundary between the expansion panel portion 3 and the solid panel portion 9, and a raised portion 23 made of a hard solid layer is formed at the tip of the upright wall 21. It is integrally formed so as to protrude higher than the panel surface 3a. In this state, the tip of the raised portion 23 is in a non-contact state with a slight gap from the chamfered portion 29c of the movable die 29. At the time of expansion molding, the thermoplastic resin R in the upright wall 21 portion is filled in advance in a direction that enlarges the cavity volume more than the surrounding area (see FIG. 3), and the plate is formed on the molding surface 29b of the movable die 29. Since it hardly pulls in the thickness direction and does not move much, it is possible to avoid the occurrence of cracks in the standing wall 21 and to ensure the strength and rigidity of the carrier plate 1.

  On the other hand, when the movable mold 29 is retracted, the slide mold 31 is urged toward the fixed mold 27 and does not retract, so that the cavity volume corresponding to the solid panel portion 9 does not expand during molding, and the fibers in the thermoplastic resin R are The elastic restoration is suppressed, and the molded solid panel portion 9 is formed into a solid solid layer 19 that does not have the expansion layer 17, and the rigidity of the solid panel portion 9 can be increased.

  In this way, the chamfered portion 29c is formed in the molding surface 29b of the movable mold 29 adjacent to the slide mold 31 so as to have a gap C between the side surface 31d of the slide mold 31 and the movable mold 29 is retracted. By simply expanding the cavity volume at the location corresponding to the expansion panel portion 3 in the mold opening direction, the strength of the light glass lifting / lowering motor mounting location (solid panel portion 9) can be achieved without significantly modifying the mold structure. The carrier plate 1 with increased rigidity can be easily formed.

  In the above-described embodiment, the case where the chamfered portion 29c of the movable mold 29 is formed with an inclined surface that is cut obliquely is shown. However, as in the modification shown in FIGS. Further, although not shown, the shape may be a convex curve toward the gap C, or conversely a concave curve.

  Further, in the above embodiment, the void is formed inside the expansion panel portion 3 by utilizing the spring back phenomenon of the fiber. However, if the foamed material is contained in the fiber-containing thermoplastic resin R, the movable die 29 is retracted. If the thickness (plate thickness) of the expansion panel portion 3 is increased by increasing the amount, that is, the expansion ratio (W), even if the restoring force (expansion pressure) of the fiber in the springback phenomenon is insufficient, The foaming force (expansion pressure) of the foamed material is preferable because the restoring force of the fiber can be complemented and a void can be formed reliably. Further, depending on the purpose of use, it is possible to mold the carrier plate 1 (resin molded body) using a thermoplastic resin in which only a foam material is mixed without mixing fibers. In these cases, examples of the foam material include a chemical foam material that generates a gas by a chemical reaction, and a physical foam material that uses an inert gas such as carbon dioxide gas and nitrogen gas.

  Furthermore, in said embodiment, although the case where the resin molding was the carrier plate 1 of the side door of a motor vehicle was shown, other automotive panels, such as an instrument panel, a door trim, a trunk board, and charged products other than a motor vehicle, It can also be applied to residential panels.

  The present invention relates to a panel-like resin composed of an expansion panel portion having a skin layer formed on the surface and an expansion layer having a large number of voids formed therein, and a solid panel portion adjacent to the expansion panel portion. It is useful for a molded body and a molding method thereof.

It is sectional drawing in the II line | wire of FIG. It is the perspective view which looked at the carrier plate which concerns on one Embodiment from the vehicle interior side. It is a shaping | molding die figure of the location corresponding to FIG. 1 which shows the state which injected and filled the thermoplastic resin in the cavity. FIG. 4 is a mold diagram in which the movable mold in FIG. 3 is slightly retracted in the direction in which the cavity volume is enlarged. It is the A section equivalent figure of Drawing 3 in a modification. It is the B section equivalent figure of Drawing 4 in a modification.

Explanation of symbols

1 Carrier plate (resin molding)
DESCRIPTION OF SYMBOLS 3 Expansion panel part 3a Panel surface 9 of expansion panel part Solid panel part 15 Skin layer 17 Expansion layer 19, 20 Solid layer 21 Standing wall 23 Raised part 25 Mold 27 Fixed mold 29 Movable mold 29b Movable mold surface 29c Chamfer 31 Slide mold 31a Molding surface 31d of the slide mold Side surface 33 of the slide mold Cavity C Clearance D Width of the chamfered portion H Height of the chamfered portion in the mold opening direction L Length of the cavity space in the mold opening direction T1 Plate of the expansion panel portion Thickness T2 Thickness R of solid panel R Thermoplastic resin W Expansion ratio of thermoplastic resin

Claims (3)

In the process of solidifying the injection-filled thermoplastic resin in the mold cavity, the cavity volume is expanded and the thermoplastic resin is expanded to form a skin layer on the surface and an expanded layer having a large number of voids. An expansion panel part formed inside,
A panel-shaped resin molded body composed of a solid panel portion formed of a solid layer adjacent to the expansion panel portion and formed without expanding the cavity volume at the time of molding,
At the time of expansion molding, by expanding the cavity volume in a state where the cavity portion corresponding to the boundary between the expanded panel portion and the solid panel portion is filled with a larger amount of thermoplastic resin in the direction in which the cavity volume is expanded than the surrounding area. The expansion panel portion is formed thicker than the solid panel portion, and a standing wall made of a solid layer standing in the thickness direction is formed at the boundary of the expansion panel portion with the solid panel portion, And a raised portion made of a solid layer is integrally formed at the leading end of the upright wall in the thickness direction so as to protrude higher than the panel surface of the expansion panel portion. A method for molding a resin molded body according to claim 1,
A fixed mold, a movable mold arranged to face the fixed mold so as to be movable back and forth, and a slide mold for forming a solid panel portion provided on the movable mold side, and the slide on the molding surface of the movable mold Prepare a molding die in which a chamfered portion is formed so that there is a gap between the side surface of the slide die in the adjacent part with the die,
With the molding die closed so that the molding surfaces of the movable die and the slide die are substantially flush with each other, the thermoplastic resin is injected and filled into the cavity of the molding die, and the thermoplastic resin is placed in the cavity. In the solidifying process, the slide mold is not retracted, but only the movable mold is retracted in the mold opening direction to expand the thermoplastic resin corresponding to the movable mold. In the molding method of the resin molding according to claim 2,
The relationship between the height (H) of the chamfered portion in the mold opening direction and the expansion ratio (W) of the thermoplastic resin is expressed by the following equation:
H ≧ W × 1 / 2mm
While satisfying
The width (D) of the chamfered portion along the molding surface of the movable mold is the following formula:
5 ≧ D ≧ 1mm
The filling,
The space length (L) in the mold opening direction of the cavity space corresponding to the expansion panel portion when the mold is closed is expressed by the following formula:
6 ≧ L ≧ 1.5mm
The molding method of the resin molding characterized by satisfy | filling.

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